Like Jays I fitted the 4.1 diff- to my 2012 4/4. Then added the full Aero Race stuff to get 163 bhp at the wheels. The Mazda box makes the most of the power.

Porsche 981 Spyder
V8 Speedster ( 5 years)
4/4 Competition spec (5 years)
4/4 4str Kent ( 10 years)